National Coral Reef Monitoring Program: Coral demographic data (adult and juvenile corals, species, colony length, condition, etc.) collected during Stratified Random Surveys (StRS) across the US Pacific since 2013 derived from in-situ diver surveys and structure-from-motion imagery (NCEI Accession 0298217)

The data described here result from benthic coral demographic surveys within belt transects of specified length and width for two life stages (juveniles and adults) across the US Pacific since 2013. This data is collected as part of the NOAA Pacific Islands Fisheries Science Center (PIFSC) and Ecosystem Sciences Division (ESD; formerly the Coral Reef Ecosystem Division) led National Coral Reef Monitoring Program (NCRMP) missions around the Mariana Archipelago, American Samoa, Pacific Remote Island Areas, and the Hawaiian Archipelago since 2013. Originally coral demographic data was derived by in-situ diver surveys, and starting in 2023 the data collection transitioned to derivation from models generated with structure-from-motion imagery.

The in-situ diver coral demographic surveys are part of the Rapid Ecological Assessment (REA) surveys for corals and fish conducted during ESD-led NCRMP missions. From 2013 to 2017, a two-stage stratified random sampling (StRS) design was used to survey the coral reef ecosystems across sub-island sectors and three depth strata (shallow: 0-6m, mid: 6-18m and deep: >18m). Starting in 2018 a one-stage StRS design was employed. These sites represent a broad range of depths (1-25 m), habitat types (aggregate reef, patch reef, pavement, rock and boulder and rubble), coral cover, and diving conditions. Allocation of sampling effort was proportional to strata area and variance in coral density. The StRS design effectively reduces estimate variance through stratification using environmental covariates and by sampling more sites rather than sampling more transects at a site. Therefore, site-level estimates and site to site comparisons should be used with caution.

Starting in 2023 coral demographic data was also derived by the GIS analysis of benthic Structure from Motion (SfM) imagery. The source imagery was collected during in-water surveys conducted by divers, and is documented separately here: https://www.fisheries.noaa.gov/inport/item/63095. During each SfM survey, an 18m transect line was deployed along the isobath and photographed using underwater cameras while swimming in a back and forth swim pattern for later processing. At depths of 0-18m, SfM surveys were conducted over a 3 x 20m area and at depths >18m, a 3 x 13m area was surveyed, both with the transect running down the middle of the survey area. The photographs were processed using Agisoft Metashape software to generate orthomosaic images that were analyzed in ArcGIS for juvenile and adult coral colony demographic metrics. SfM imagery was not submitted as part of this archive package.

The data provide information on adult coral colony counts, morphology, size, partial mortality (old and recent dead), presence and causation of disease and other compromised health conditions, including bleaching. Juvenile colony surveys include morphology and size. Taxonomic identification of adult colonies is to the lowest taxonomic level possible and genus level for juveniles. Some segment observations were repeated for internal quality control starting in 2019, and indicated with a repeat segment flag and transectnum = -999; use column OG_OR_RPT_SEG to filter for only original segments. Refer to data dictionaries for details on column conditions.

The raw data also include individual observations of crustose coralline algae diseases and Alcyonarian disease type and lesion size as well as the presence of other Anthozoans, such as other cnidarians including Alcyonareans, Zoantharians, Corallimorpharians, and Antipatharians (does not apply to PMNM surveys conducted in 2014 and 2015 or surveys conducted after 2017).